Various fire retardants are known. Compositions are known that typically contain fire suppressing salts such as an ammonium phosphate or ammonium sulphate for aerial applications to combat forest fires. See, U.S. Pat. Nos. 3,196,108; 3,257,316; 3,309,324; 3,634,234; 3,730,890; 3,960,735; 4,447,336; 4,447,337; 4,606,831; 4,822,524; 4,839,065; 4,983,326 and 6,162,375. Other are known to have fire suppressants such as carbonaceous matter, organic phosphorous compounds, organic halides, or borates. See, U.S. Pat. Nos. 4,668,710; 4,686,241; 5,246,652; 5,968,669; 6,001,285; 6,025,027; 6,084,008 and 6,130,267.
As can be appreciated, in addition to fire retardants used to combat forest fires, intended as a temporary measure to be washed away once the fire threat is minimized, prevention of the spread of fire is an important consideration sought in many everyday materials and construction applications such as paper, fabrics, wood, and many plastics. Much research has been conducted to determine how to reduce and/or eliminate the potential fire hazards caused by these materials.
In general, all organic and some inorganic materials will burn under appropriate conditions. With solid materials, this involves decomposition of the solid to produce gases that burn, rather the burning of the solid per se. The actual burning occurs in four main stages:
1. Heating: an ignition sources raises the temperature of the item;
2. Decomposition: when sufficiently heated, the item begins to change its properties and break down, forming combustible gases;
3. Ignition: combustible gas production increases until a concentration is reached that allows for sustained, rapid oxidation, when exposed to an ignition source; and
4. Combustion and propagation: combustion of the gases becomes self-propagating if the heat generated is sufficient to be radiated back to the item and continue the decomposition process.
Decades ago, most furnishings in the home were made from natural materials including wool, cotton, and horse hair, which were relatively flame resistant; so, if a fire started in the home, it would generally take some eight to ten minutes before flashover would occur, depending on the location of the fire, and availability of flammable materials in close proximity to the source of the fire. If discovered quickly enough, the fire department would arrive to extinguish the blaze before it grew too rapidly and flashover occurred. Flashover, of course, occurs when the rate of combustion and flame spread in the dwelling becomes so rapid that the air becomes super heated, which causes all exposed flammable surfaces to erupt into flames, i.e., “flash over.” This produces the equivalent of an explosion, blowing out doors and windows, and causing serious bodily injury of death. Nowadays, most everyday household materials are extremely flammable themselves, being made not only of paper and wood but also synthetic fabric and plastic, the latter, or course, made from petroleum products. Thus, flashover is of increasingly serious concerns. Some of these modern materials may practically burst in flames with a short exposure to the ignition source, and flashover may occur before the fire department can get to the home, even if notified promptly. As can readily be appreciated, therefore, the residential fires of today may be quite tragic when compared to those of past years.
In addressing this, conventional intumescent systems have been developed. They typically include as essential components: (1) an acid-forming substance, which may be referred to as a “catalyst”; (2) an expanding agent, which causes formation of a foamed (intumescent) layer by emission of an inert or non-combustible gas, which agent may be referred to as a “spumific”; and (3) a binder such as a thermoplastic resin, which contributes to the film-forming properties of the system and provides a portion of a char skeleton, and which is usually referred to as a “carbonific.” A component may have more than one function. Such phosphate-catalyzed intumescent compositions can be composed of components selected from among the following:
1. As the acid source (catalyst), usually amino phosphates, mainly ammonium polyphosphates, ammonium orthophosphate, and melamine phosphate, say, in an amount of about 25% by weight of the total formulation.
2. As the spumific, melamine, melamine salts, melamine derivatives, urea and/or dicyandiamide.
3. As the carbonific, a polyhydroxy compound, usually a polyol, which is decomposed by liberated phosphoric acid to form an ester that results in formation of the char (carbonification), for example, pentaerythritol, dipentaerythritol, tripentaerythritol, or certain sugars, starches or starch derivatives.
Two disadvantages with these conventional systems are cost and opacity. Opaque compounds such as ammonium polyphosphate in powder form, powdered amines and carbonific components are often employed. These tend to be not only expensive, owing to the materials and their labor-intensive production, but also less desirable aesthetically, say, on woodwork where its exposed surface if sought after as an architectural feature.
In address of the foregoing, Mabey, in U.S. patent application No. 10/132,958 filed on Apr. 24, 2002 A.D., disclosed a fire retardant, which, in general, is a composition comprising a mixture of a substantially neutral ammonium phosphate salt in combination with an active hydrogen-containing nitrogenous organic compound, and with a hydroxyl-containing carbonific. It can be made by contacting a phosphoric acid with ammonia to form the ammonium phosphate, contacting the ammonium phosphate with the active hydrogen-containing nitrogenous organic compound and the hydroxyl-containing carbonific under conditions sufficient to form the composition; and can be used by contacting it with a flammable substrate under conditions sufficient to be flame retardant. Also disclosed was an article of manufacture comprising, in combination, the fire retardant composition and the flammable substrate or a residue of the same. Typical amounts of weight of preferred components effective therein are listed as follows:
Mono/diammonium phosphates  20~70%Diluent (solvent) of water  25~50%Urea 2.5~15.0%Glucose 4.0~12.0%Polysaccharide resin 2.0~40.0%GLUCOPON-425 surfactant 0.2~1.2%Potassium salicylate solution0.01~0.1%.
The composition of the Mabey '958 application is indeed highly effective and desirable. However, it would be desirable to improve upon the art.